Coincidence blocking tube oscillator



1951 J. "H. MULLIGAN, JR, ET AL 2,570,836

COINCIDENCE BLOCKING TUBE OSCILLATOR Filed Oct. 18, 1947 OUTPUT OSCILLATOR HOPJZONTAL 8.0. GRHD WAVE.

H; \\\\\-I\|L DELAYED(3.SPSECQEQUALJZING TRIGGERS FRomsHApER.

T-F l I 5 LINE DELAYED HOFHZONTAL DR\\/\NG PULSES;

ATTORNEY Fatented Oct. 9, 1 951 2,570,836 v *COINCIDENCE BLOCKING TUBE OSCILLATOR V 7 James H. Mulligan, Jr., East Orange, and Arthur J. Talamini, -Jr., Caldwell Township, Essex County, N. J.,assignors'to Allen B. Du Mont Laboratories, ,Inc., Passaic, N. J., a corporation of Delaware Application October 18, 1947, Serial No. 780,641

This invention relates to a blocking tube oscillator that is particularly useful in television systems.

In a television synchronizing signal generator it is sometimes necessary to generate pulses that occur at exactly one half the rate of other pulses but delayed a half a line with respect to these pulses. It is the object of this invention to generate such pulses. This invention is particularly useful in the system described in application, Ser. No. 780,638, filed of even date herewith, entitled Television Synchronizing Signal Generator, now U. S. Patent No. 2,556,933, although its use is not restricted to this system.

The invention may be understood from the description in connection with the accompanying drawing in which:

Fig. 1 is a diagram of connections illustrating the invention, and

Fig. 2 are diagrams of several pulses that are used.

In the drawing, reference character I indicates a pentode vacuum tube having a cathode 2, plate 3, control grid 4, screen grid and suppressor grid 6. The plate 3 is connected to one end of winding I of a transformer 8, the other end being connected to a source of positive potential and to the screen grid 5. Another winding 9 of transformer 8 i grounded on one side, the other side being connected to a source of delayed equalizing pulses of the sort shown as waveform TE in said application. This waveform and its relation to other waveforms used in this device are shown in Fig. 2.

Voltage from the control grid of oscillator i3 which has the waveform shown as TD in Fig. 2, is applied through condenser II and across resistor I2 to suppressor grid 6 of tube I.

The control rid 4 is connected through resistor l5 to adjacent ends of resistors I4 and H3. The other end of resistor I4 is connected to ground. The other end of resistor I6 is connected to a source of negative potential. Grid 4 is also connected through condenser l! to one end of winding of transformer 8, the other end thereof being grounded. The output is taken off between condenser l1 and the ungrounded end of winding 10. It has the form shown as TF in Fig. 2.

The operation is as follows:

The first equalizing pulse TE (Fig, 2) applied to winding 9 has no effect because the differentiated grid wave TD, which is obtained from the horizontal blocking oscillator l3, simultaneously applies negative potential to the sup- 7 Claims. (01.25047 pressor grid 6 and prevents oscillation. By the time the next pulse TE arrives the pulse TD is no longer sufficiently negative to block oscillation. by the time the third equalizing pulse Tn; arrives the grid wave TD has again applied a negative potential to the suppressor grid 6 so that the third pulse is not passed. This cycle is repeated and gives an output waveform which is shown as TE. This output represents the delayed horizontal driving pulses which are mixed with vertical driving pulses and used to control the variable delay multivibrators of the sort described in the application mentioned above that are used to generate driving pulses for the sweep generators in each pick-up unit mentioned therein.

What is claimed is:

1. A device of the character described comprising an electron discharge device having a cathode, a plate, a control grid, a screen grid and a suppressor grid, a source of positive potentiai, said screen grid and plate being connected to said source of positive potential, said control grid being connected through resistance to a source of negative potential an oscillator adapted to operate at a predetermined frequency and supply a signal to said suppressor grid, a transformer having three windings, one of said windings being connected between the plate of said discharge device and said source of positive potential, another one of said winding being connected from ground to the control grid of said discharge device through a capacitor 'and the third winding being connected between ground and a source of triggering pulses, the polarity relationship of said windings being such that changes in plate current in said device is aided by the resultant grid circuit voltage.

2. The device of claim 1 in which said oscillator operates at half the frequency of said triggering pulses.

3. The device of claim 1 in which the voltage from said oscillator has a sawtooth wave shape.

4. The device of claim 5 in which n equals 2 whereby the frequency of the output of said tube is one half the frequency of said second signal voltage.

5. A blocking oscillator including a tube having a plurality of electrodes, a source of first signal voltage of a predetermined frequency, said signal voltage having a sawtooth wave form of negative polarity, said source of first signal voltage being connected to one of said electrodes to cause said oscillator to remain quiescent, a source of second signal voltage having a frequency n times the frequency of said first signal voltage, said second signal voltage comprising a series of regularly occurring pulses, said source of second signal voltage being connected to another of said electrodes to co-act with said first named voltage to cause said blocking oscillator to fire at 1/11 times the frequency of said second signal voltage.

6 An electron discharge device having a plu-e rality of electrodes and connected as a blocking oscillator, a first one of said electrodes being connected to a first input voltage source, and a second one of said electrodes being connected to a second input voltage source, said first input voltage having a sawtooth Wave form in which the vertical going portion of said sawtooth wave is negative to bias negatively said first electrode, and said second input voltage comprising a series of regularly recurring pulseshaving a repetition rate twice that of the repetition rate of said sawtooth Wave, said device being activated only when-said pulses, coincide in time with a positive going portion of said sawtooth waves '7. The device of claim 6 in which alternate ones of said pulses occur immediately following the negative going portion of said sawtooth wave.

JAMES H. MULLIGAN, JR. ARTHUR J. TALAMINI, JR.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 2 ,19761825 Geiger Apr. 9, 1940 2,227,008 Schlesinger Dec. 31, 1940 2,265,825 Urtel-et a1. Dec. 9, 1941 2,284,714 Bedford June 2, 1942 2,358,297 Bedford Sept. 19, 1944 2,447D82 Mill'r Aug. 17, 1948 2,464,259 Proskauer Mar. 15, 1949 2,468,058

Grieg Apr. 26, 1949 

